An Etymological Dictionary of Astronomy and Astrophysics

A wave that travels backward in time according to Maxwell’s electromagnetic theory; it arrives before it is transmitted. → Maxwell’s equations have two solutions, the normal solution
describes the ordinary waves, called → retarded waves, traveling forward in time. However, no advanced waves have ever shown up in any experiment. The advanced solutions of Maxwell’s equations are usually simply discarded as “unphysical.”

Etymology (EN): Advanced, adj. from advance, →
advance of perihelion; → wave.

Etymology (PE): Mowj, → wave; pišras “advanced,” from piš “before,” Mid.Pers. peš

• ras “arriving,” from rasidan “to arrive,” Mid.Pers. rasitan, O.Pers./Av. rasa- present stem of ar- “to move, go or come toward,” cf. Skt. ar-, rcchati.